The present invention relates generally to wire preparation tooling, and more particularly to a machine for preparing the free ends of multi-stranded wire conductors for welding.
Multi-conductor, jacketed cables are used widely in the electronics industry to interconnect various electrical devices together. These multi-conductor cables contain a plurality of wires that may be terminated to connector contacts, connector bus bars, support blades or the like to form a connector. Often each conductor of these multi-conductor cables has an inner core comprised of multiple conductive strands surrounded by an outer insulative covering. In most instances in the assembly of these conductors, the wires are individually attached, such as by welding or soldering, to a corresponding plurality of electrically conductive contacts. Soldering of the wires is a tedious and time-consuming task and the soldering process itself lends itself to potential contamination of the connector contacts.
When the free ends of these multi-strand wires are attached to a set of contacts by resistance welding, the wire strands must be twisted together so that the free ends have enough body to resist the electropressure generated by such welding. This twisting has heretofore been accomplished by manual labor and, as such, it is a tedious labor-intensive and time-consuming task that increases the cost of wire preparation. This wire preparation and attachment process must often be repeated when the connector utilizes rows of contacts such as the LFH ("low insertion force helix") connectors made by Molex Incorporated of Lisle, Ill., the assignee of the present invention. Such a connector is described in U.S. Pat. No. 4,740,180, issued Apr. 26, 1988 to Molex. The number of wire attachments in such connectors may range from about 10 individual attachments to about 200 individual attachments.
The preparation of the free ends of the cable wires is currently performed by hand. This method is costly for it is labor intensive and it is prone to irregularities because the wires are twisted by hand and uniform twisting and stripping of the wires is therefore hard to obtain.
The present invention is directed to a wire preparation assembly that prepares a plurality of multi-strand wires for welding by stripping the wires, twisting the exposed wire strands and cutting the wires to an appropriate length for welding. In this preparation, the wire insulations are stripped to a specific length, the wire strands are twisted simultaneously for the same number of rotations and the wires are clearly cut to a uniform proper length.